import { useState, Fragment } from "react";
import reactLogo from "./assets/react.svg";
import viteLogo from "/vite.svg";
import "./App.css";

/**
 * 函数式组件
 */
function App() {
  // useState
  //    一个 hook
  const [count, setCount] = useState(0);

  // 返回一段 html | jsx | ReactElmenet | VNode | VDOM

  // <>   一个空标签，叫做 Fragment ,用于包裹，类似Vue中的 template 元素

  // JSX 中要使用 JS表达式，通过单个花括号
  return (
    <Fragment>
      <div>
        <a href="https://vitejs.dev" target="_blank">
          <img src={viteLogo} className="logo" alt="Vite logo" />
        </a>
        <a href="https://react.dev" target="_blank">
          <img src={reactLogo} className="logo react" alt="React logo" />
        </a>
      </div>
      <h1>Vite + React</h1>
      <div className="card">
        <button onClick={() => setCount((count) => count + 1)}>
          count is {count}
        </button>
        <p>
          Edit <code>src/App.tsx</code> and save to test HMR
        </p>
      </div>
      <p className="read-the-docs">
        Click on the Vite and React logos to learn more
      </p>
    </Fragment>
  );
}

export default App;
